
void setup(){
  pinMode(13,OUTPUT);
  pinMode(7,OUTPUT);
  pinMode(5,OUTPUT);
  pinMode(2,OUTPUT);
  Serial.begin(9600);
  Serial.println("Program Started!");
}

void loop(){
 static int seconds  = 0;

 writeLight(13, seconds & 1);
 writeLight(7, seconds & (1<<1));
 writeLight(5, seconds & (1<<2));
 writeLight(2, seconds & (1<<3));
 seconds++;
 delay(1000);
}

void writeLight(int pin, int value){
  digitalWrite(pin, value);
} 
